"For me, burnout means not only being tired of your job, but also inability to ‘burn' outside work."
"burn outside work"? What does that mean?
Burnout is feeling great distress at doing your job, due to factors such as overwork, disillusionment, and depression. Sometimes that adverse feeling is so intense the employee is psychologically unable to continue.
As much some people would like to fancy themselves as coldly logical automatons, human action is actually in great part motivated by feelings. So feelings matter.